Mass Shootings in the USA

Mass shootings are more common in the United States than many other developed countries. When mass public shootings occur, they often attract national attention, and lead some to wonder whether Americans are becoming more violent. The following five facts highlight the types of mass shootings as well as their violence, and answer whether mass shootings are on the rise.

Mass shooting = 4 or more victims murdered with firearms, in one incident, in one or more locations in close proximity. (The offender is not counted as a victim if he/she dies.)

Note: Definition matters because it specifies what one is talking about, and is one key to determining whether or not mass shootings are on the rise. A word of caution though: definitions can vary and change. The above definition comes from Krouse & Richardson 2015.

What Are the Kinds of Mass Shootings?

Krouse & Richardson distinguish three kinds of mass shootings:

Public shootings occur in one or more public places (e.g., streets, churches, schools, workplaces) and are not “attributable to any other underlying criminal activity or commonplace circumstance (armed robbery, criminal competition, insurance fraud, argument, or romantic triangle).”

Familicide mass shootings in which most or all victims are family members (most commonly an intimate partner and children), and are not “attributable to any other underlying criminal activity or commonplace circumstance (e.g., armed robbery, criminal competition, insurance fraud, argument, or romantic triangle)

Thus, the number of incidents has consistently risen decade by decade since the 1970s, but the deadliness has not. Given the small number of mass shootings (small relative to the total number of firearm murders) per year, one particularly violent mass shooting (e.g., the 2012 Newtown, CT school shooting) can bump up the yearly average number of killed and/or wounded.

Note: The vast majority of mass shootings are committed by one person. An incident can last minutes, hours, or days.

Most Common Mass Shootings: Familicides

Between 1999 and 2013 in the USA, familicide mass shootings were the most common, accounting for 40% (127 incidents) of all mass shootings over the period, compared with 39% (124 incidents) for other felony mass shootings, and 21% (66 incidents) for public ones.

Most Violent but Least Deadly Mass Shootings: Public Shootings

Attempts to kill are generally more successful with guns rather than knives, fists, or other weapons. But among mass shootings, in 1999-2013 in the USA, familicides were the most deadly, ending in 576 total killed vs. 37 wounded. Other felony mass shootings are also deadly (532 killed vs. 75 wounded). Public mass shootings are least deadly (446 killed vs. 329 wounded).

In short, in 1999-2013, among the three types of mass shootings, public shootings involved the most dead and injured combined, but the least dead.